Phenomenology and Early Course
Recent follow-up studies focus on the early course and are pointing in the same direction. Weiser et al. reported 27% of later schizophrenics to present premorbidly with a diagnosis of affective disorder (as compared with a prevalence of less than 10% in the population). The most detailed and convincing analysis of the relationship between depression and schizophrenia in the early course of both disorders emerges from the Mannheim ABC study.[3**] Depressive symptoms and syndromes were found to be the first premorbid signs in patients who were later on treated for schizophrenia. Now there is evidence that depression is a risk factor for transition to psychosis among vulnerable patients.[3**,4]
Unfortunately, detailed investigations in the early course of bipolar disorder are missing. The follow-up studies in bipolar disorder by Angst et al.,[5*] however, suggest a similar constellation for bipolar disorder by proposing depressive episodes to initiate the course of manic-depressive illness in the majority of cases.
Other risk factors appear to be less comparable: the first population-wide study in bipolar disorder did not reveal any factor of significant influence besides family history and early parental loss. Multiple risk factors were obtained for schizophrenia in the same population without any overlap with bipolar disorder. Another study[8*] exploring cognitive achievements of conscripts before entering the period of risk for both disorders reported deficits in visuospatial performance as a precursor of both disorders; diagnosis-specific risk factors were also reported: good arithmetic reasoning was predictive of bipolar disorder but not of schizophrenia. Altogether, Weiser et al.[9*] concluded that cognitive impairments before the onset of both disorders lack specificity.
Curr Opin Psychiatry. 2006;19(2):165-170. © 2006 Lippincott Williams & Wilkins
Cite this: Schizophrenia and Bipolar Disorder: Differences and Overlaps - Medscape - Mar 01, 2006.